When using !Sub or !Ref in the 'Enabled' property in when 'Schedule' of AWS::Serverless::Function.

[stanfan1992]

Description:

!Sub or !Ref in the 'Enabled' property in when 'Schedule' of AWS::Serverless::Function, it cannot be transformed correctly. The AWS::CloudWatch::Rule will always use 'ENABLED' for State property

Steps to reproduce:

Launch the template below:

Transform: AWS::Serverless-2016-10-31
Parameters:
  TriggerState:
    Type: String
    Default: false
    AllowedValues:
      - true
      - false
Resources:
  ExampleLambda:
    Type: AWS::Serverless::Function
    Properties:
      FunctionName: example
      Handler: example
      Runtime: python3.8
      CodeUri:
        Bucket: myBucket
        Key: Lambda.py.zip
      Events:
        LambdaSchedule:
          Type: Schedule
          Properties:
          Name: lambda-trigger
          Schedule: cron(0 4 * * ? *)
          Description: description
          Enabled: !Sub ${TriggerState}

Observed result:

After the template is transformed/launched with 'false' to 'TriggerState', the property State of AWS::CloudWatch::Rule will be 'ENABLED'

Expected result:

As I passed 'false' for Enabled, the AWS::CloudWatch::Rule property State should be disabled.

Additional environment details (Ex: Windows, Mac, Amazon Linux etc)

1. OS: Mac
2. If using SAM CLI, sam --version: SAM CLI, version 1.15.0
3. AWS region: us-east-1

Add --debug flag to any SAM CLI commands you are running

[stanfan1992]

These code could be the problematic part.
https://github.com/aws/serverless-application-model/blob/develop/samtranslator/model/eventsources/push.py#L120-L121

[stanfan1992]

Add a workaround:

Since the issue is not successfully transforming the template with the intrinsic function we have workaround:

Using Fn::Transform to call a AWS::Include transform. Use the AWS::Include transform, which is a macro hosted by AWS CloudFormation, to insert boilerplate content into your templates. The AWS::Include transform lets you create a reference to a template snippet in an Amazon S3 bucket.

Please check the below SAM template samples:
--- template.yml ---

Transform: AWS::Serverless-2016-10-31
Parameters:
  S3Bucket: 
    Type: String 
  TriggerState:
    Type: String
    Default: false
    AllowedValues:
      - true
      - false
Resources:
  ExampleLambda:
    Type: AWS::Serverless::Function
    Properties:
      FunctionName: example
      Handler: example
      Runtime: python3.8
      CodeUri:
        Bucket: <MyBucket>
        Key: Lambda.py.zip
      Events:
        LambdaSchedule:
          Fn::Transform :
            Name : AWS::Include
            Parameters :
              Location : 
                Fn::Sub: "s3://${S3Bucket}/${TriggerState}.yml"

--- true.yml ---

Type: Schedule
Properties:
  Name: lambda-trigger
  Schedule: cron(0 4 * * ? *)
  Description: description
  Enabled: true

--- false.yml ---

Type: Schedule
Properties:
  Name: lambda-trigger
  Schedule: cron(0 4 * * ? *)
  Description: description
  Enabled: false

[MarcGuiselin]

I can reproduce this issue on v1.19.1 (via github actions)

Another workaround is to conditionally set the cron job to run on a past date like so:

Type: Schedule
Properties:
  Name: lambda-trigger
  # Workaround for disabling schedule
  Schedule: !If
    - TriggerState # Condition
    - cron(0 1 * * ? *) # 1:00 AM UTC or a custom schedule here
    - cron(0 1 1 1 ? 1970) # Never run
  Description: description
  Enabled: True

[pappnase99]

Just ran into this issue, more than a year later. Still happening in version 1.46.0.

[hoffa]

You might be able to get this to work by adding AWS::LanguageExtensions to Transform as such:

Transform:
  - AWS::LanguageExtensions
  - AWS::Serverless-2016-10-31

AWS::LanguageExtensions resolves intrinsic functions if the value is known when Transforms are run.

See #2533 for more information.

[hoffa]

Closing in favor of #2533.